implicit / implicit.py

#    Copyright 2011 Dexetra <contact@dexetra.com>

#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.

#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.

#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.

from sqlalchemy.schema import ForeignKeyConstraint
from sqlalchemy.event import listen


class ImplicitForeignKeyConstraint(ForeignKeyConstraint):

    def __init__(self, columns, refcolumns, primary_key=None, **kwargs):
        super(ImplicitForeignKeyConstraint, self).__init__(
                columns, refcolumns, **kwargs)
        self.primary_key_flag = primary_key

    @staticmethod
    def _add_columns(constraint, table):
	referenced_table = table.metadata.tables[
		    constraint.elements[0].target_fullname.split('.')[0]]
	for column, element in zip(constraint.columns, constraint.elements):
	    new_column = getattr(
		    referenced_table.c,
		    element.target_fullname.split('.')[1]).copy()
	    new_column.name = column
	    new_column.key = column
	    if constraint.primary_key_flag is not None:
		new_column.primary_key = constraint.primary_key_flag
	    table.append_column(new_column)


listen(ImplicitForeignKeyConstraint, "before_parent_attach",
       ImplicitForeignKeyConstraint._add_columns)

def example_main():
    from sqlalchemy.schema import Column, Table
    from sqlalchemy.types import Integer
    from sqlalchemy.engine import create_engine
    from sqlalchemy.ext.declarative import declarative_base
    from implicit import ImplicitForeignKeyConstraint
    Base = declarative_base(bind=create_engine('sqlite://', echo=True))
    class A(Base):
        __tablename__ = 'a'
        id = Column(Integer, primary_key=True)
    class B(Base):
        __tablename__ = 'b'
        #id = Column(Integer, primary_key=True, autoincrement=False)
        __table_args__ = (ImplicitForeignKeyConstraint(['a_id'], ['a.id']),)
    t = (Table(
            'c', Base.metadata,
            #Column('id', Integer, primary_key=True, autoincrement=False),
            ImplicitForeignKeyConstraint(['id'], ['a.id'], primary_key=False)))
    class D(Base):
        __tablename__ = 'd'
        id = Column(Integer, primary_key=True, autoincrement=False)
        __table_args__ = (ForeignKeyConstraint(['id'], ['a.id']),)
    print Base.metadata.tables
    Base.metadata.create_all()

if __name__ == "__main__":
    example_main()
Tip: Filter by directory path e.g. /media app.js to search for public/media/app.js.
Tip: Use camelCasing e.g. ProjME to search for ProjectModifiedEvent.java.
Tip: Filter by extension type e.g. /repo .js to search for all .js files in the /repo directory.
Tip: Separate your search with spaces e.g. /ssh pom.xml to search for src/ssh/pom.xml.
Tip: Use ↑ and ↓ arrow keys to navigate and return to view the file.
Tip: You can also navigate files with Ctrl+j (next) and Ctrl+k (previous) and view the file with Ctrl+o.
Tip: You can also navigate files with Alt+j (next) and Alt+k (previous) and view the file with Alt+o.